Control of a relay chain circuit



Jan. 21, 1969 o. HILLMANN 3,423,637

CONTROL OF A RELAY CHAIN CIRCUIT Filed June 8, 1966 ffffffff United States Patent St 24,021 U.S. Cl. 317-26 4 Claims Int. Cl. H02h 3/08; 7/00 ABSTRACT OF THE DISCLOSURE The relays of a chain circuit are connected to an energizing circuit, starting with the second relay, via contacts closed by the immediately preceding relay. If one or several relays fail due to operation of an associated fuse or circuit breaker, the succeeding relays are energized via a contact closed by the fuse or circuit breaker.

The present invention relates to the control of a chain circuit, and particularly of a chain circuit consisting of a plurality of switching means. More specifically, the first switching means is operated directly via an input contact and each further switching means is operated via a contact of the respective preceding switching means. Each of the switching means is protected by a fuse equipped with a switch.

In electro-mechanical devices it is necessary in many cases to control a plurality of similar switching means by actuating an input contact. If all these switching means are connected with the input contact, the load for the contact may be too heavy.

Depending on the number of switching elements, the elements may be subdivided into groups and each group may be controlled through one or several contacts of an inserted chain of switching means. Depending on the field of application, the switching elements may include relays, circuit breakers, fuses having external contact elements and other making devices. It may be necessary to introduce a delay to prevent all the switching means from being energized simultaneously, and thus to protect the current supply facility against an undesirably heavy surge.

To solve this problem it is known to concentrate the inserted switching means into a chain in which only the first switching means is actuated via the input contact and each following switching means is operated via a contact of the preceding switching means. To protect the inserted switching means a fuse or circuit breaker is provided in its coil circuit. Thereby protection of the switching means is obtained, but if the fuse responds or blows, not only the respective switching means fails, but also the switching means following in said chain, because their starting circuits are interrupted.

It is a primary object of the invention to provide a circuit arrangement in which all desired functions are maintained and whereby the undesired interruption of a chain is avoided.

This is achieved according to the invention so that, when the fuse of a switching means blows, the switching means following next in the chain is actuated via a make-contact controlled by the fuse.

The circuit arrangement is now describe-d with the aid of an example, shown in the figure and used in telecommunication and telephone engineering, respectively.

The coil circuit of relay A1 is closed by actuating the "ice input contact zK via the fuse contact sil of the fuse Sil. The fuse used is of the general kind employed in alarm circuits in which rupture of the heating element releases a spring which closes a second contact thus completing an alarm circuit. In the present instance, a break in the fuse heating element operates a spring to close a contact and complete a ground connection for a relay. The fuse is shown in its non-operative position. The relay A2 is energized via a make-contact al of the relay A1 and the fuse contact si2 of the pertinent fuse Si2. This process is continued within the chain until the final relay An has responded. If a fault now occurs in a coil circuit causing the response of the pertinent fuse and de-energizing the relay, the corresponding fuse will close a contact to couple a circuit for the succeeding relay. For example, if relay A2 is disturbed, the coil circuit of relay A3, held closed via the contact 02 of the relay A2 is interrupted, but via the fuse contact .912 of the fuse Si2 which has operated, the relay A3 and all following relays can respond or hold in operation.

In a special construction in which the input contact is provided as a pulse contact of a clock pulse generator, the circuit serves to control counting pulse generators being connected as similar switching elements to the contacts (all anl to alm anm) of the inserted relays (Al An).

While the principles of the invention have been described above in connection with specific apparatus and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.

What is claimed is:

1. A chain circuit comprising a plurality of switching means,

an input contact,

a first switching means responsive to signals transmitted through said input contact to close a second contact,

a second switching means responsive to signals transmitted through said second contact to close a third contact,

'a fuse in series with each of said first and second switching means to open said corresponding switching means in case said fuse blows,

each fuse including a make contact switch connected between the input contact and the succeeding switching means to close upon operation of the fuse and thereby enable said succeeding switching means to stay in operative condition.

2. A chain circuit substantially as claimed in claim 1,

in which said first switching means includes a control winding with one winding end connected to one pole of a voltage source via a first fuse and the other winding end connected to a break contact of the switch of said first fuse, and the movable portion of the first fuse switch is connected with the opposite pole of the voltage source via the input contact.

3. A chain circuit substantially as claimed in claim 2,

in which the movable portion of the fuse switch of each succeeding fuse after the first is connected on the one hand with a voltage source of opposite polarity through the make contact of the preceeding switching means and the fixed portion of the corresponding fuse switch is connected on the other hand with the make-contact of the preceding fuse switch.

4. A chain circuit substantially as claimed in claim 3,

in which 3 4 the input contact is a contact of a clock pulse generator 3,315,127 4/ 1967 Lenz 31726 controlling via said chain circuit contacts of con- 3,315,129 4/ 1967 Fisher 317-26 necting pulse generators.

JOHN F. COUCH, Primary Examiner.

References Cited 5 R. V. LUPO, Assistant Examiner.

UNITED STATES PATENTS us. C1.X.R. 2,861,222 11/1953 Hodtum 317-26 3,045,168 7/1962 Fellendorf 31726 3,262,018 7/1966 Bogacrts et al. 317-49 

